Cocking bolt of machine guns



Jan. 11, 1949.

F. w. vsAMPsoN ET AL 2,458,647

COOKING BOLT OF MACHINE GUNS Filed Aug; l5, 1946 3 :E l" '96 /03r /0 6 A f l ,97 4 A 6 /As 6 96 98 96 52 6l 4 i'zzc" 40 FREDERICK W. EMVIFIEIJN7 EEDRGEIIHYDE,

Patented Jan. l1, 1949 COOKING BOLT OF MACHINE GUNSl Frederick W. Sampson, Dayton, Ohio, and George J. Hyde, Brooklyn, N. Y., assignors, by mesne assignments, to the United States of America as represented by the Secretary of War Application August 15, 1946,. Serial No. 690,738

(Cl. ll2'-16) 2 Claims.

which the bolt is operated by recoil forces. It is designed in the present instance specifically for use with a gun illustrated in our copending application of August 14, 1946, Serial No. 690,518, in which the breech bolt is operatedy by blow back. The present invention is concerned with the means for operating the breech bolt for the rst shot, or in case of failure in operation of the iiring mechanism to complete any shot.

In the gun mentioned, as may be found to be the case in many others to which my invention would be applicable, -the breech bolt reciprocates in a housing, and a cocking slide is provided to move the breech bolt to recoil position manually, so that the sear may engage. This movement involves the formation of a slot in the side of the housing for the handle of the cocking slide, and to close the slot, normally a bar is formed on the cooking slide to close the slot. The breech bolt recoils a distance greater than the length of the slot, and rearward of the cocked position, but it is desired to keep the closure piece engaged slidably with the breech bolt throughout recoil of the latter. This would require the cocking slide to be too long to move to full cocking position in a simple casing made. to accommodate only the normal recoil movement of the bolt. It is. therefore the purpose of the present invention to so construct the cocking slide that its necessary movement may be effected, and yet its slidable engagement with the breech boltpreserved throughout reciprocation of the latter.

A further important aim of the invention is to present a novel construction of the cooking slide and a novel coordination thereof with a simple snap latch to enable self-return of the slide to normal position inoperative during reciprocation of the breech bolt ordinarily, but yieldable to manual operation when required.

Additional objects, advantages and features of invention reside in the specification construction, arrangement and combination of the parts involved in the embodiment of the invention, as will be apparent or understood from the following description and theV accompanying drawings, wherein:

Figure 1 is a fragmentary side elevation of a fire-arm constructed in accordance with. the invention, with portions broken away to show the essential trigger and sear parts in relation to the breech bolt;

Figure 2 is a horizontal longitudinal section on 2 the line 2-2` of Figure 1, with the parts in` normal position; I

Figure 3 is a similar View with the parts in cooking position;

Figure 4 is a cross section on the line 4 4 of Figure 1;

Figure 5 is a fragmentary cross section on the line 5--5 of Figure 1.

Referring more particularly to the drawings, there is illustrated a firearm comprising a receiver l as in our said other application, Xed coaxially with which there is a rearwardly eX- tending breech bolt housing 3, the latter being a simple cylindrical tube closed at its rear end by a manually removable cap I4 having a bayonet slot engagement at l5 with a block I 6 welded to the top of the housing, the latter carrying a rear sight illl'. Slidingly fitted in the housing 3 there is a breech bolt body E, which is a substantially solid cylinder, and as described in said other application and usual in automatic arms, this breech bolt is urged forward by a conventional driving spring, these last details not being illustrated, since they comprise no novel part of the present invention. As also described in said other application, the breech bolt body is relieved at its forward under part and for-med with a stopflug 5| against which the heel 52 ofthe sear engages to hold the breech bolt cocked, and a tripper element on the trigger proper 5l engages under the toe 56 of the sear to move the latter to let oli in a familiar function. The trigger and sear structure being no novel part of the present invention are not further described or illustrated, and details of a spring and safety device 86 more particularly described in said other application are not dealt with in detail herein.

The breech bolt body 6 is formed with a longitudinal channel 96 in the right hand side thereofY extending throughout its length, having parallel uipiper and lower sides and a vertical inner bottom surface. The housing 3 has a longitudinal slot 91 cut therein in alignment with the channel 9By and extending from the extreme forward end of the housing rearwardly, Where it is enlarged upwardly and downwardly as at 91 forming a rectangular opening. A cocking slide 95 is provided having a handle 94 extending outwardly through the slot from within the housing 3 and tted snugly between the sides of the slot for sliding movement therein, its outer part being enlarged closely adjacent the periphery of the housing to a form and size corresponding to those of the enlargement and opening 91', yso

that when the handle is at the rear limit of its movement and the breech bolt is out of the way the handle may be pressed inwardly through the enlargement 97 for removal. The handle is formed with an integral bar 94 extending longitudinally within the housing 3 and adapted to fit slidingly in the channel 96 of the breech bolt, its inner side adapted to lie close to the said vertical bottom face of tli'e channel, while its outer side is adapted and arranged to lie close against the edge portions of the housing Srabove and below the slot S1. When the slide is at itsforward limit of movement, its rear end also `laps the housing beyond the rear end of the slot 91. The portion of the receiver i around which the housing 3 is fitted is also relieved in line with the slot 91 so that a portion of the base of the handle 94 may extend forwardly beside the relieved.v

part. The underlying part `of the receiver is radially bored and tted with a spring-pressed bullet latch device IllI, a convex nose portion of which engages with a dimple lill in the overlying part of the handle 94 to hold the latter at its forward-most position yieldable to manual operation when desired.

The breech bolt body 6 has a cocked position as illustrated Iin Figures l and 2, in which its forward part extends a short distance forwardly beside the bar 94 and under the slot STI. At forward or battery position o1" the breech bolt it engages the rear breech face IIlD of the receiver I. A cooking lug 98 is formed on the base of the handle 94 extending inwardly close beside this breech face of the receiver and the forward end of the` breech bolt 6 is recessed as at 93 to receive the lug 93. Thereby, when the handle is drawn rearwardly the lug 98 moves the breech bolt rearwardly also. The barSM is bored from its rear end, and has engaged slidably therein a rod |62, which connes a helical spring 1&3 in the forward part of the bore. The latter tends to thrust the rod rearwardly from the bore but extension of the rod is limited by means 0f a cross pin Iifi inserted through the bar, and across a space in the bore beside the rod afforded by a relieved side port-ion il of the rod, this relieved part stopping short of the inner end of the rod so that the shoulder thus formed engages the pin wh-en the rod is fully extended. The rod at its extended position projects rearwardly a distance sufcient to remain in the channel 96 while the slide is at its forward limit when the breech bolt recoils to its maximum rearward position as dotted at 6 in Figure 2. The inner side of the bar 94 is relieved as at H5 from top to bottom. At its rear part and xed on the inner side of the rod extending from the extremity of the rod forwardly there is a block IIB, the Vertical dimension of which is suiicient to engage slidingly against the upper and lower faces of the channel S5, the relieved part I I5 and the length of the block i IB being such that the rod may be pressed forwardly by the cap I4 to such distance as necessary when the handle 94 is moved to the rear end of the slot 91. The block IIE has a radial dimension with respect vto the breech bolt I3 which is only a small part of the radial depth of the channel S6, and the top and bottom portions of the bar 94 adjacent the relieved part H5 -occupy the remaining space in the channel outwardly of the block whenever the breech bolt is at cocked position. However, when the breech bolt recoils to its maximum limit lit will move beyond the body of the bar 94', and will receive only the block l I5 therein.

Due to this mutual functional relation of the cooking slide and breech bolt, the cooking slide may be depended upon to hold the breech bolt against rotation around its longitudinal axis, so that extractor and ejector devices may function properly in relation to the discharge port 25 for spent cartridge cases, in a conventional way. Also, the lug 5I is kept aligned with the sear 53.

It is thus made possible to embody a gun action and housing of extreme simplicity, and low cost; but perhaps most important, to enable complete sealing of the housing, which conventionally is closed in guns of this type by some form of closure which is opened during firing of the arm, this detail not being iillustrated here. In place of a special closure, the breech bolt may be left at battery position when the arm is being ported, the forward part of the bolt tting snugly in the bore of the receiver I as disclosed in the said other application.

The receiver I, is formed with an axial bore 5, at the left side of which an ejector not shown is fixed movable through a clearance cut or groove 26 in the'lei't side of the reduced forward part' 4 of the breech bolt, so as to engage the butt of a spent cartridge held by the conventional extractor IU at the upper side of the bolt 4. An ejection port 25 is formed in the upper right side of the receiver, through which the spent cartridge is `thrown by the ejector on recoil of the breech bolt in a familiar way.V W-hen the breech bolt is in battery, its portion 4 will close the port 25.

The housing is slotted at its lower side as at 3', and it will be noted that the sear is of such form as to completely close this last named slot; The pivotal point of the sear being so located that its top part over the pivot lies close to the under side of the housing at the forward part of this slot, while the rear part of the sear is at all times inclined upwardly into the housing, with a substantially vertical rear end face at the heel 52, which face lies close to the rear end edge of the slot at all positions of the sear.

An unusually well closed housing for the bolt is thus provided when the gun parts are assem bled as shown.

As may be seen from Figures l and 4, the trigger assembly is enclosed by the `stock 34 and the trigger frame 40 at all sides except the top, and therefore when the housing and receiver are assembled to the stock and trigger frame as shown the trigger action is completely enclosed also. The trigger assembly is open at its upper side so that when the housing with its receiver on the one hand, and the stock and trigger frame on the other hand are detached, the trigger parts are exposed .sufficiently for ordinary inspection and cleaning.

The function yof the spring I 03 is such that when the handle is pulled to its rearmost or cooking positiorrand released abruptly, the reaction of the spring between lthe cooking slide and end of the rod while the latter bears against the cap I4, is such that the cooking slide is thrust rapidly forward, and after the rod is checked against the pin |04 the greater mass of the handle and bar parts is such that the 'cooking slide will continue its forward motion rapidly, by momentum, until the dimple lllI engages over the bullet'latch IIJI, retaining the cooking slide at this forward position until its next manual operation is required. As will be apparent, the breech bolt 6 in its semi-automatic or automatic nring functions may continue its reciprocation without impedance by, or disturbance of, the cooking slide.

While we have described a specific embodiment of the invention in the best form known to us, it will nevertheless be understood that this is purely exemplary, and that changes in construction, arrangement and combination of the parts, substitution of materials and equivalen-ts, mechanical or otherwise, may be made without departing from the spirit of the invention as dened in the appended claims, wherein,

We claim:

1. In an arm of the character described, a cooking device comprising a slide having a longitudinal body provided at its forward end with a handle extending through and slidably tted in a longitudinal slot formed in the side of a breech bolt housing of said arm, said forward end being formed for engagement with the forwardly facing part of a breech bolt of said arm, said longitudinal body having a longitudinal bore eXtension from its rear end to slidably receive an extensible member, means within said longitudinal body to limit the movement of said extensible member within said longitudinal body and yielding means'positioned in said bore for resilient engagement of said extensible member with said longitudinal body, said extensible member and longitudinal body slidable together and parallel with said breech bolt housing to eect 1 cooking of said bolt.

2. In a machine gun having a breech bolt housing in which the breech bolt is reciprocable 6 therein, said housing provided with a longitudinal slot, a cooking device comprising a slide having a longitudinal body formed at its forward end with a handle and a lug disposed in opposite direction to said handle, said handle extending through and slidably tted in said longitudinal slot, said lug adapted to engage the forwardly facing part of said breech bolt, a longitudinal bore starting from the rear end of said body and extending into it to slidably receive an extensible bar member, means within said body to limit the movement of said bar within said body and spring means positioned in said bore for resilient engagement of said bar with said body, said lbar and said body movable together and parallel with said bolt to elect cooking of said bolt, said spring returning said bar and body to precocking position.

FREDERICK W. SAMPSON. GEORGE J. HYDE.

REFERENCES CITED The following references are of record in the rile of this patent:

UNITED STATES PATENTS Number Name Date 1,895,719 Lahti Jan. 31, 1933 2,224,928 Reising Dec. 1'7, 1940 2,342,824 Swebilius Feb. 29, 1944 2,407,157 Hyde Sept, 3, 1946 2,425,684 Patohett Aug. 12, 1947 

